1. Field of the Invention
The present invention relates to a battery capacity calculation method of an intelligent battery, the intelligent battery and a portable electronic device at least equipped with a current measurement circuit and calculating battery capacity based on a current value measured thereon.
2. Description of the Related Art
Conventionally, various intelligent batteries have been known, which are equipped with a CPU, a timer, a current measurement circuit, a voltage measurement circuit, a thermal measurement circuit and so on and always monitoring a consumption current (a current flowing from a battery) and a charging current (a current flowing into the battery) in modes by using these circuits so as to always grasp capacity data. Such an intelligent battery is used as a power supply of a notebook-sized PC for instance.
In recent years, it has become necessary in the notebook-sized PC to add a soft-off state to power supply modes in supporting ACPI proposed by Microsoft Corp. In this soft-off state, while a current of approximately 3 to 4 mA that is a minute current flows, it has been difficult to correctly detect the current value on the current measurement circuit of the conventional intelligent batteries.
As for problems of inability to correctly detect the current value, characteristics such as a voltage offset, a temperature drift and so on of operational amplifiers comprising the current measurement circuit can be named. In addition, there has been a problem that a circuit of high performance cannot be incorporated since it is necessary to mount a CPU and other circuits in a battery pack and there is only limited space. Furthermore, there has also been a problem that the operational amplifiers of high precision are expensive and it is costly to configure a circuit of high performance capable of detecting such a minute current.
Thus, problems that the current value could be read in spite of no current actually flowing, and the current value could not be read in spite of a current flowing have occurred, to name a few. Consequently, a problem that the longer the soft-off state is, the greater an error of the capacity data managed in the intelligent battery becomes has occurred.
An object of the present invention is to provide a method of calculating capacity of the intelligent battery, the intelligent battery and portable electronic device that solve the above-mentioned problems and are capable of allowing for power consumption by a minute current undetectable by a conventional circuit without any special cost required so as to consequently allow the error of the capacity data to be smaller.
A method of calculating capacity of an intelligent battery of the present invention relates to a method of calculating capacity of the intelligent battery at least equipped with a current measurement circuit to measure an electric current value on which calculation of battery capacity is based. By the method of calculating capacity of the intelligent battery of the present invention:
(1) when a system using the intelligent battery shifts from an normal operational mode to a low electric power consumption mode, the system sends a notice to the battery that it shifts to the low electric power consumption mode and also sends a consumption electric current value or a consumption electric power value in the low electric power consumption mode unique to the system;
(2) the intelligent battery performs subtraction of capacity data based on the received consumption electric current value or consumption electric power value in the low electric power consumption mode, and disables capacity calculation by the current measurement circuit on the other hand;
(3) when the system using the intelligent battery shifts from the low electric power consumption mode to the normal operational mode, the system sends a notice to the battery that it shifts to the normal operational mode and also stops the subtraction of capacity data based on the consumption electric current value or consumption electric power value in the low electric power consumption mode, and enables capacity calculation by the current measurement circuit on the other hand.
In the present invention, the capacity data in the low electric power consumption mode such as during a soft-off mode is calculated, rather than capacity calculation based on the current value measured by the current measurement circuit of the battery itself, based on the capacity data acquired by multiplying the consumption electric current value in the low electric power consumption mode acquired in advance by the length of time and voltage for the mode to continue or the capacity data acquired by multiplying the consumption electric power value in the low electric power consumption mode acquired in advance by the length of time for the mode to continue, so that the battery capacity in the low electric power consumption mode can be correctly calculated and the error of the acquired capacity data can be made smaller.
As preferred embodiments of the present invention, there is an aspect in which the low electric power consumption mode is a soft-off state or a suspended state in ACPI, and a form wherein the intelligent battery is SBS-compliant and a notice of the mode shifting from the system to the battery and a notice of the consumption electric current value or consumption electric power value in the low electric power consumption mode are sent by defining OptionalMfgFunction 1 of SBS. In either case, the method of calculating capacity of the intelligent battery of the present invention can be easily performed.
Another preferred embodiment of the present invention is handling of the intelligent battery in the case where it is drawn out of the system during the low electric power consumption mode. The following shows two preferred examples. In either case, the method of calculating capacity of the intelligent battery of the present invention can be performed in a preferable manner even if the battery is drawn out of the system.
As a first method, in the low electric power consumption mode:
(1) on detecting that the intelligent battery is drawn out of the system, the subtraction of capacity data based on the received consumption electric current value or consumption electric power value in the low electric power consumption mode is stopped;
(2) next, on detecting that the intelligent battery is connected to the system, the intelligent battery counts time from the connection; and
(3) when the system using the intelligent battery shifts from the low electric power consumption mode to the normal operational mode:
(a) the system sends a notice to the effect that it is reconnected to the intelligent battery and also sends the consumption electric current value or consumption electric power value in the low electric power consumption mode unique to the system;
(b) it calculates capacity to be subtracted from the reconnection from the received consumption electric current value or consumption electric power value and the counted time, and subtracts the calculated capacity to be subtracted from the capacity data; and
(4) next, the system sends a notice to the intelligent battery to the effect that it shifts to the normal operational mode and also stops the subtraction of capacity data based on the consumption electric current value or consumption electric power value in the low electric power consumption mode, and enables capacity calculation by the current measurement circuit on the other hand.
As a second method, in the low electric power consumption mode:
(1) on detecting that the intelligent battery is drawn out of the system, the intelligent battery stops the subtraction of capacity data based on the received consumption electric current value or consumption electric power value in the low electric power consumption mode;
(2) next, on detecting that the intelligent battery is connected to the system:
(a) the system recognizing the connection sends a notice to the effect that it is reconnected to the intelligent battery and also sends the consumption electric current value or consumption electric power value in the low electric power consumption mode unique to the system;
(b) the intelligent battery resumes subtraction of capacity data based on the received consumption electric current value or consumption electric power value in the low electric power consumption mode, and disables capacity calculation by the current measurement circuit on the other hand;
(3) when the system using the intelligent battery shifts from the low electric power consumption mode to the normal operational mode, the system sends a notice to the battery that it shifts to the normal operational mode and also stops the subtraction of capacity data based on the consumption electric current value or consumption electric power value in the low electric power consumption mode, and enables capacity calculation by the current measurement circuit on the other hand.
Moreover, another example of the method of calculating capacity of the intelligent battery of the present invention is characterized by including the steps of:
(1) on a shift of the system from the normal operational mode to the low electric power consumption mode and thereafter to the normal operational mode, calculating on the system side consumption battery capacity data assumed to have been spent during the low electric power consumption mode based on the consumption electric current value or consumption electric power value in the low electric power consumption mode unique to the system.
(2) sending consumption battery capacity data from the system side to the above described intelligent battery side;
(3) on the above described intelligent battery side, calculating current battery capacity based on the above described consumption battery capacity data.
Furthermore, the intelligent battery equipped with the above-mentioned capacity calculation method and a personal computer equipped with the intelligent battery are preferable since they can make the error of the battery capacity data smaller.